1. Technical Field
The disclosure relates to an optical film. More particularly, the disclosure relates to a patterned retarder.
2. Description of Related Art
Patterned retarder (or micro retarder) is an optical film having different microstructures respectively located on odd-row areas and even-row areas of the optical film. The phase difference of the odd- and even-row areas is usually λ/2. For example, the phase of the odd- and even-row areas may be 0 and λ/2, respectively, or λ/4 and −λ/4, respectively. Therefore, when the patterned retarder is attached to the outer surface of a display, the patterned retarder can transform the polarization state of pixels located on the odd and even rows to display 3D images.
The patterned retarders are firstly prepared by molding process. A phase retarder is formed first, and then the phase retarder on the odd-row areas or the even-row areas is removed by a knife to make the phase difference of the odd-row areas and the even-row areas to be λ/2.
Liquid crystal ISO phase preparing method, which is a method for preparing film with optically birefringent and isotropic regions, includes coating a liquid crystal layer on an entire substrate first. Next, the odd-row areas or the even-row areas are irradiated by light to make the phase angle of the odd-row areas or the even-row areas to be λ/2. Next, the rest of the liquid crystal layer is heated to be in an ISO phase and then cured by heat to make the retardation to be zero.
As for the dual-regions alignment method, which is a method for fabricating a patterned retarder having two different states of alignment, the method uses rubbing or optical ways to make the alignments of the odd-row areas and the even-row areas to be different. Thus, the phase difference of the odd-row areas and the even-row areas is λ/2.
The methods described above, the liquid crystal molecules located on the interfacial areas between the odd-row areas and the even-row areas usually have a derangement problem. The derangement problem can cause light leakage to form bright lines on the images of the display, and the quality of the displayed 3D images is thus decreased.